How many counties are there in New Jersey?

21.

The County and City Data Book 2007, published by the US Census Bureau, reports that New Jersey has 21 counties. The largest counties are Ocean and Burlington, with areas of 916 and 819 square miles, respectively. Bergen, Middlesex and Essex are the counties with the highest population numbers: 904,037, 786,971 and 786,147, respectively. Salem has the least number of residents: 66,595.